This invention relates generally to a packing or seal assembly for sealing the annulus between the side wall of a hollow cylindrical member and the outside wall of a second cylindrical member disposed concentrically therein, and more particularly, to a pressure energizeable seal assembly having capability for bi-directional sealing in both axial directions.
The seal assembly of this application is intended for use in sealing applications where bi-directional sealing is essential as in spool type valves, crossover seals in wellhead assemblies, or sub-sea applications. Pressure energized seals wherein sealing capability is enhanced with increasing pressures are well known as are bi-directional seal assemblies.
Seal assemblies which utilize the principle of concentrating the total force of fluid pressure acting on the seal assembly to a smaller area of sealing surface and thereby amplifying the compressing force and sealing effect of the sealing surface are also known. One such "unsupported area" seal, as these seal assemblies are sometimes referred to, is shown in U.S. Pat. No. 4,262,690. However, the seal shown therein is uni-directional in that it is adapted to seal in only one axial direction of application of fluid pressure.
It is therefore an object of the present invention to provide a pressure energizeable sealing assembly for sealing an annulus between two cylindrical objects for either axial direction of application of fluid pressure.
It is another object to provide a pressure energizeable sealing assembly for sealing an annulus between two cylindrical surfaces wherein the sealing assembly comprises a plurality of contiguous packing rings sandwiched between a pair of retainer rings and the surface of a retainer ring adapted to be exposed to fluid pressure is of larger surface area than the surface of the adjacent packing ring which is exposed to the retainer ring whereby the fluid force applied to the retainer ring and sealing assembly from either axial direction and which is transmitted to the packing rings is amplified to increase the compression and sealing effect of the packing rings.